Most wall mounted soap dispensers include a housing, which is adapted to retain a refill unit including a container of soap and associated pump mechanisms that dispense soap through a dispensing spout upon their actuation. The housing is mounted to a wall, and the pump mechanisms are actuated through movement of a push bar pushed toward the wall. The dispensing spout is located between the push bar and the wall such that the push bar moves in a lateral direction closer to the dispensing spout upon actuation of the pump mechanisms. The dispensing spout also typically moves upwardly during actuation, thus raising the dispensing spout vertically relative to the push bar. Because of this relative movement between the push bar and the dispensing spout, the push bar sometimes collects soap during dispensing. This is particularly problematic when a foamed soap is dispensed, because the foam stream exiting the dispensing spout tends to spread in width and flutter side-to-side due to the physical forces acting to create the foam and the properties of the foam itself. Soap left on the push bar can grow germs that can come into contact with the end user or dispenser serviceman.
It is somewhat common to modify the shape of the push bar to prevent the push bar from getting too close to the erratic path of the foamed soap, but such modifications can increase dispenser production costs and limit the industrial design options for the push bar shape. Thus, a need exists for a pump mechanism that is actuated in a manner that reduces, and preferably eliminates, the tendency for soap to collect on the push bar of the dispenser.
The refill unit, which includes a container of product to be dispensed and an associated pump that is actuated to dispense the product, typically carries a reciprocating piston pump, wherein a piston member of the pump reciprocates relative to stationary portions of the pump in order to trap a fixed amount of the product and then displace that trapped volume into and out of the dispensing tube. In order to reduce the overall footprint of the refill unit, the stationary portions of these reciprocating piston pumps often extend into the container of the refill unit. As a result, the volume of product that can be carried by the container is reduced by the volume occupied by elements of the pump. Additionally, because these pumps must have an inlet communicating with the product in the container in order to draw the product into the pump, either product is wasted when the level of the product falls below the inlet to the pump or special adaptations must be made to place the inlet to the pump at a position where the vast majority of the contents of the container can be drawn into the pump. For instance, in some refill units, a dip tube of the reciprocating piston pump is curved 180° to place the inlet of the dip tube near the bottom of the refill container. In others, a shroud is employed to the same effect, the shroud having a conduit communicating with the lower regions of the container. While this helps to ensure that less product is wasted, the extension of pump mechanisms into the container volume decreases the amount of product that the container can carry. Thus, there is a need in the art to maximize the useful volume of a container by decreasing the amount of wasted space within the volume of the container, thus maximizing the amount of product that the container can hold.
The volume occupied by a refill unit is also a consideration for shipping purposes. For purposes of shipping product, it is important to maximize the amount of product that can be shipped in a given shipment. Thus, there is a need in the art to increase the useful volume of a refill unit while maintaining an acceptable shipment volume of the refill unit.
Typically, foam pumps provided as part of a soap dispenser refill unit include an air pump portion and a liquid pump portion integrated together. The refill unit will carry a foam pump comprised of an air pump portion and a liquid pump portion, and the dispenser housing will carry elements for retaining the refill unit and elements for actuating the foam pump. It has been found that providing the air pump portion as part of the foam pump carried by the refill unit is not necessarily cost effective. The air pump portion adds to the size, weight and cost of the refill unit, especially in high output dispensers. Accordingly, there is also a need in the art for foam dispensing systems that employ a disposable liquid pump portion, as part of a refill unit, and a more permanent air pump, as part of a dispenser housing.